1. The Field of the Invention
The present invention relates generally to fiber optic communication. More specifically, the present invention relates to methods, apparatuses, and systems for providing robust fiber optic packages, components, and assemblies.
2. The Relevant Technology
Fiber optic technology is increasingly employed in the transmission of data over communication networks. Networks employing fiber optic technology are known as optical communications networks, and are typically characterized by high bandwidth and reliable, high-speed data transmission.
To communicate over an optical communications network using fiber optic technology, fiber optic components such as fiber optic transceivers are used to send and receive optical data. Generally, a fiber optic transceiver can include one or more optical subassemblies (“OSA”) having an optical transducer, such as a transmitter optical subassembly (“TOSA”) having an electro-optical transducer for sending optical signals, and a receiver optical subassembly (“ROSA”) having an opto-electronic transducer for receiving optical signals. More particularly, the TOSA receives an electrical data signal and converts the electrical data signal into an optical data signal for transmission onto an optical network. The ROSA receives an optical data signal from the optical network and converts the received optical data signal to an electrical data signal for further use and/or processing. Both the ROSA and the TOSA include specific optical components for performing such functions.
In particular, a typical TOSA includes an optical transmitter such as a light emitting diode or a laser diode located on a header, for transmitting an optical signal to an optical fiber. A monitor diode may be included on the header to receive at least a portion of the optical transmission of the optical transmitter for providing feedback related to the optical transmission. The optical transmitter is typically covered by an at least partially transparent cap that protects the optical transmitter while allowing the optical transmitter to transmit the optical data signal to the optical cable. The cap may include a lens for focusing the optical signal transmission.
A typical ROSA includes an optical receiver, such as a PIN photodiode or avalanche photodiode (“APD”), located on a header. The optical receiver is typically covered by an at least partially transparent cap that protects the optical receiver and allows the optical receiver to receive an optical data signal from an optical cable. The cap may include a lens for focusing the optical signal transmission received from the optical cable.
The TOSA and ROSA components are assembled into packages and the packages typically include a plastic barrel to align and couple the end of a fiber optic cable for transmission of an optical signal to the optical receiver, or from the optical transmitter. When assembled into packages, the TOSA and ROSA assemblies may be subject to temperature extremes and various forces in a number of directions. These forces may be applied in an axial direction, for example, to electrical leads, often called feed throughs, which supply power to the optical components located upon the header. The TOSA and ROSA assemblies must maintain optical alignment for maximum power transmission notwithstanding these forces and conditions.
One common type of component is the TO-Can component. The TO-Can component comes in several different sizes and configurations. Referring to FIG. 1, a typical TO-Can 1, for example a TO-46 style component, is shown. The TO-Can 1 has a tilted window 2. The TO-Can 1 has relatively short vertical sidewall sections 3 followed by relatively long sloped sidewall sections 4. The sloped sidewall sections 4 are sloped inward toward the center of the component prior to joining the tilted window 2 located on the top of TO-Can 1.
Referring now to FIG. 2, a cross sectional illustration of a TO-Can 1 (from FIG. 1) assembled into an LC package 10, for example a TO-46 LC package, is shown. The TO-Can 1 includes a header 5, a monitor diode 6, and a vertical cavity surface emitting laser (“VCSEL”) 7. The LC package 10 also includes a barrel 8. The barrel 8 has an open first end 8A that is sized and configured to receive the TO-Can 1, and an open second end 8B that is sized and configured to receive an optical fiber 9. The barrel 8 is further configured to align the optical fiber 9 with an optical transmission from the VCSEL 7. According to this embodiment, the tilted window 2 is angled so as to reflect a portion of the optical transmission from the VCSEL 7 to the monitor diode 6.
As shown in FIG. 2, the TO-Can 1 is attached to the barrel 8 using a welding epoxy 11. The welding epoxy 11 is applied about the bottom of the TO-Can 1. The mechanical stability of the TO-Can 1 within the open end 8A is dependent on the strength of the bond between TO-Can 1 and barrel 8 created by welding epoxy 11.
Referring now to FIG. 3, a side view illustration of a TO-Can 12 (e.g. a TO-56 component) is shown assembled into an LC package 13 (e.g. a TO-56 LC package). A welding epoxy 11 has been used to attach a header 14 of the TO-Can 12 to a barrel 15 of the LC package 13. Typically a bead of welding epoxy 11 is beaded on surface 18 to fill the gap 17 between the header 14 and the barrel 15 similar to that discussed above with respect to FIG. 2.
Industry standards continue to decrease the size of fiber optic components and optical packages, while increasing port density. As component size decreases, the ability to maintain alignment between components through temperature extremes becomes increasingly more difficult. In some environments, the typical method of beading a welding epoxy to secure the TO-Can component to a barrel of a fiber optic package does not provide the stability needed to withstand axial loads under various temperature conditions. Thus, when the movement due to axial loads is great enough to cause misalignment (e.g., of a VCSEL with a corresponding optical fiber caused by movement of a TO-Can and barrel relative to each other), optical power loss during optical transmission can occur.
Therefore, what would be advantageous are methods, apparatuses, and systems for robust fiber optic packages, components, and assemblies.